descartes

Descartes

Use Shapely_ or GeoJSON-like geometric objects as matplotlib paths and patches

.. image:: http://farm4.static.flickr.com/3662/4555372019_9bbed1f956_o_d.png :width: 800 :height: 320

Requires: matplotlib, numpy, and optionally Shapely 1.2+.

Example::

from matplotlib import pyplot from shapely.geometry import LineString from descartes import PolygonPatch

BLUE = '#6699cc' GRAY = '#999999'

def plot_line(ax, ob): x, y = ob.xy ax.plot(x, y, color=GRAY, linewidth=3, solid_capstyle='round', zorder=1)

line = LineString([(0, 0), (1, 1), (0, 2), (2, 2), (3, 1), (1, 0)])

fig = pyplot.figure(1, figsize=(10, 4), dpi=180)

1

ax = fig.add_subplot(121)

plot_line(ax, line)

dilated = line.buffer(0.5) patch1 = PolygonPatch(dilated, fc=BLUE, ec=BLUE, alpha=0.5, zorder=2) ax.add_patch(patch1)

#2 ax = fig.add_subplot(122)

patch2a = PolygonPatch(dilated, fc=GRAY, ec=GRAY, alpha=0.5, zorder=1) ax.add_patch(patch2a)

eroded = dilated.buffer(-0.3)

GeoJSON-like data works as well

polygon = eroded.geo_interface

>>> geo['type']

'Polygon'

>>> geo['coordinates'][0][:2]

((0.50502525316941682, 0.78786796564403572), (0.5247963548222736, 0.8096820147509064))

patch2b = PolygonPatch(polygon, fc=BLUE, ec=BLUE, alpha=0.5, zorder=2) ax.add_patch(patch2b)

pyplot.show()

See also: examples/patches.py.

Descartes is not associated with the identically named and apparently defunct project at http://descartes.sourceforge.net/.

.. _Shapely: http://gispython.org/lab/wiki/Shapely